One thing that would help is if you could say more about how you know Samuel was born in 1764.
Back then, people weren't necessarily keeping track of their age the same as we do nowadays.
If that 1764 was the result of doing math from his age on an 1850 census, he could easily have lost those few years as time went by.
Before looking for another marriage for his father, it would be good to find all source documents that mention his age or year of birth, and see how that lines up.
Cheers
Shirlea